Fortress Biotech, Inc. Annual report pursuant to Section 13 and 15(d)

Annual report pursuant to Section 13 and 15(d)

Organization and Description of Business - Additional Information (Detail)

Organization and Description of Business - Additional Information (Detail) (USD $)	0 Months Ended	1 Months Ended	12 Months Ended			1 Months Ended
	Aug. 12, 2014	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014	Apr. 18, 2014	Mar. 17, 2014	Jun. 16, 2014
Organization And Nature Of Business [Line Items]
Long-term Investments			$ 4,160,000us-gaap_LongTermInvestments	$ 0us-gaap_LongTermInvestments		$ 4,160,000us-gaap_LongTermInvestments		$ 250,000us-gaap_LongTermInvestments
Equity Method Investment, Ownership Percentage								35.00%
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	50,000		3,218,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net	293,000	293,000
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	293,000
Equity Method Investments, Fair Value Disclosure			4,160,000			4,160,000
Payments to Acquire Short-term Investments			346,000	0	0
CB Pharma Acquisitions Corp [Member]
Organization And Nature Of Business [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases			2,675,000
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)			1,200,000
Sale Of Stock Number Of Insider Shares Issued In Transaction		1,100,000
Stock Repurchased During Period, Shares		100,000
Proceeds from Issuance Initial Public Offering						42,900,000
Sale of Stock, Number of Shares Issued in Transaction						265,000
Sale of Stock, Price Per Share			$ 10.00			$ 10.00
Exercise Price Of Warrants			11.50%
Proceeds from Issuance of Private Placement						2,700,000
Business Combination, Step Acquisition, Equity Interest in Acquiree, Including Subsequent Acquisition, Percentage			23.00%			23.00%
Equity Method Investments, Fair Value Disclosure			3,900,000			3,900,000
Payments to Acquire Short-term Investments		25,000
Employee Stock Option [Member]
Organization And Nature Of Business [Line Items]
Payments to Acquire Short-term Investments							243,000
Nuro Pharma Inc [Member] \| Bridge Loan [Member]
Organization And Nature Of Business [Line Items]
Loans Receivable Interest Rate									8.00%
Financing Receivable, Recorded Investment, Current								$ 50,000